The invention lies in the field of pneumatic, hydraulic, electrical and other control systems for vehicles and fixed installations.
In conventional practice in electro-pneumatic systems design engineers tend to place pneumatic and electro-pneumatic control components in positions most convenient (e.g. nearest) to the actuators that they control. The benefit of quick reaction times is achieved by use of short pneumatic tubes, which are important in some applications, e.g. in feedback control loops and others where significant response hysteresis is experienced. However, locating pneumatic and electro-pneumatic control components near the actuators that they control often exposes them to a harsh environment.
In fixed applications electrical components may not be located in explosive or fiery environments nor in corrosive environments. For example, packaging machinery, which uses pneumatic actuators requires the electrical components to be In an isolated enclosure because spray painting and other sources of flammable mixtures in the air occur. Corrosive environments also obtain and would cause rapid deterioration of electrical components if exposed to them.
In vehicle applications, heat, dirt, oil, physical blows and vibration are typical of the harsh environment conditions, which are not conducive to reliable long-term performance of the components.
Electro-pneumatic components require air supply and delivery tubing as well as electrical connections for control functions. Complicated electrical harnesses have to be made and installed to provide electrical interconnections between various components. Pneumatic components have to be mounted on small, precise mounting brackets located inside hostile environments, like an engine compartment. During mounting of major components like machinery, e.g. engines and gearboxes in vehicles, these are often damaged and have to be repaired/replaced or otherwise reworked during installation and/or assembly. Time consuming work by qualified technicians is required in assembly and installation, maintaining high standards of reliability of the work. For example, in an assembly line the connections of pneumatic lines and electrical wiring harnesses and connections have to be made, requiring lengthy time periods and testing procedures. The tubes and wiring harnesses have to be channelled through the vehicle firewall from the engine compartment to the cab where the driver utilizes the controls. Different vehicle models require variations in control systems, resulting in a large number of different components, hole configurations, assembly procedures and reliance on extensive and detailed knowledge by technicians and accurate implementing of this in assembly work on the production line. Assembly/installation time, cost and quality are all adversely affected.
While these approaches to pneumatic installations are being continued to be used, the inventor has perceived the need to address the problems inherent in them. The solution of these problems is provided by the invention of a concept of general application, as herein defined in the appended claims.
While this discussion centres on pneumatic installations, the invention can in principle be applied in hydraulic installations, where similar considerations apply.
According to the invention, an electro-pneumatic installation is provided characterised by an integrated pneumatic manifold in the form of a single block, perforated by a plurality of internal channels that are variously oriented in three dimensions and selected for a defined installation, the block adapted to be mounted in a single opening in a fire wall of a vehicle or other mounting of a stationary installation, the block having provision made on its obverse and reverse faces for mounting of electro-pneumatic relays and components, with connections for electrical wiring at its obverse face and pneumatic tubing to the electro-pneumatic relays and components, for supply of pneumatic air to input channels of the block and for receiving pneumatic control air from output channels of the block.
The effect of this approach, is that the electro-pneumatic control components are not mounted in the vicinity of where they must do their work, but on the obverse side of the block and tubing is connected from the reverse side of the block, to the actuators to which the pneumatic actuation must be applied, for example, hydraulic equipment and other actuators. Although a time delay is therefore experienced down the length of the tubing, it is found that in many applications, for example in particular in vehicle applications, the distance down the tubes is not so long as to pose any problem at all. Where required such delays can be negated by selecting larger orifice valves, fittings and tubing to allow higher flow rates.
In addition, the electro-pneumatic relays are mounted on the obverse side of the block and wiring harnesses have only to bring electrical wiring to that side of the block, and not into the engine compartment to a multiplicity of locations or analogously in a stationary installation. The advantage of a central point for all wiring connections is achieved. The electro-pneumatic relays can be located in protected environments, for example, in the case of vehicles, on the obverse side of the block that faces e.g. the air conditioned space of the driver""s cab, which is usually mounted on sprung and shock absorbing mountings.
The passages of the block replace a multiplicity of connectors, such as inline connectors, tee pieces, brackets connectors and many others. As a result, the leakage risk of such connectors is eliminated and the number of fittings is dramatically reduced. The air connections of the electro-pneumatic components made to the block can be tested in the factory, on a test bench, in a speedy and reliable way. The block can be supplied with a test certificate verifying the correct functional operation of all components before installing the integrated pneumatic manifold (IPM) into the vehicle or machine.
An aperture in a vehicle firewall or the installation cabinet for the block can be of a single dimensioning that can be standardised for many different models of vehicle or installation and the differences catered for by blocks that have the same outside dimensions but different internal passages, with their components already installed.
As a result, much skill and knowledge need not be required in the assembly line or installation procedures, reducing the levels of skill required, for reliable and quality installations. In effect, the skill, knowledge and quality are built into the block and its attached components, in the fabrication and assembly of the block, where these requirements can be more easily met and controlled. For example, machining of the block can be specified completely in the software programming of a CNC machine, so that repeatable reliability and quality can be assured at much lower cost and much less human factor involved. The machining of the block is complex, but using manufacturing batch numbers and a unique serial number for each design as well as engraved labels for various port connections add further assembly and servicing advantages.
The invention also allows selection of interface sealing type of components, which do not require to be screwed into the block with a turning motion imparted to the component. This allows reduction of the block size to a minimum and simplifies servicing and maintenance.
Selection of all electrical components for connections to be made with screw-on captive type plugs allows for fast original connection and replacement without the danger of connections loosening due to vibration.
It is possible by the use of the block to re-design some functions in order to improve safety and reliability. Additional functions such as an air supply for inflating tyres, in the case of application to a vehicle, and connections for possible optional extra equipment at a later stage, can be provided.
Assemblies such as non-return valves, shuttle type valves and restrictor orifices can be designed into the block, instead of being provided as separate components which have to be connected in line.